Many vegetation trimming and edging devices make use of a cutting element, such as a plastic string, that is rotated at high speed to cut vegetation such as grass or weeds. Trimming generally refers to the cutting of vegetation in a substantially horizontal swath. Edging generally refers to the cutting of vegetation with a substantially vertical swath to produce a more precise edge, e.g., for defining the border of a lawn adjacent a driveway or sidewalk.
The user adjusts the cutting device between horizontal and vertical orientations for trimming or edging. Physically tilting the cutting device to the proper orientation can be awkward, however, and cause muscle strain. For this reason, many cutting devices offer an adjustable working member, or "head," that can be manipulated between the trimming and edging positions.
The head is mounted at the end of a shaft that extends from the head to a handle that is gripped by the user. The head typically contains a motor and a rotor to which the cutting element is attached. The handle includes a switch for actuation of the motor. By rotating the head about the shaft, the user can adjust the orientation of the cutting element, but maintain the orientation of the handle gripped by the user.